1. Field of the Invention
The present invention relates generally to tools and equipment, for maintaining and sharpening cutting implements, and more specifically to an automated sharpener for sharpening the blade of a band saw, with the blade remaining in place on the saw during the sharpening operation. The device is mounted on the saw and extended from its normally retracted position for sharpening the blade. Once the initial setup adjustments are made, the device may be automated to sharpen the cutting edge of each tooth of the saw, automatically shutting off when all of the teeth have been sharpened. The device eliminates any need for removal of the blade from the saw for sharpening.
2. Description of the Related Art
Powered saws of various types are used in the timber industry, as well as for various other operations where wood cutting is required (pallet construction and dismantling, etc.). One type of saw which is commonly used in these industries is the band saw, where a flexible toothed metal band is rotated between two wheels or drums, and the cutting is accomplished by the free portion of the band or blade between the two wheels.
Any saw blade, including those of band saws, will become dull over some period of time, depending upon the type of wood being cut. (hard or soft wood, knots, etc.), the type of operation, and other factors. Conventionally, this requires removal of the band from the saw for its transportation to a maintenance shop where the blade may be resharpened. Obviously, this results in increased down time for the saw, as the blade must be removed and a second sharpened blade installed in order to keep the sawing operation going. Oftentimes, the installation of another blade also requires that the blade be aligned and adjusted when it is installed, thus requiring additional down time for the saw. Accordingly, many band saw operators will keep their saw in operation past the optimum efficiency of the blade, with the blade becoming quite dull. This produces an inferior cut and slows the cutting action, but to a point, it is more efficient than removing and replacing the blade for sharpening.
Accordingly, a need will be seen for a means of sharpening a band saw blade with the blade remaining installed on the saw. The present invention provides this function, by means of a retractable sharpening unit which is extended to engage the saw blade when sharpening of the blade is needed. Once the present sharpener has been set up and adjusted for the particular blade on the saw (band width, tooth spacing, etc.), and the sharpening process started, the sharpening process is fully automated until each tooth of the blade has been sharpened. At this point, the device automatically shuts off, and the operator retracts the device for later use.
A discussion of the related art of which the present inventor is aware, and its differences and distinctions from the present invention, is provided below.
U.S. Pat. No. 889,289 issued on Jun. 2, 1908 to Charles Wright, titled "Band Saw Sharpener," describes a manually operated device having at least one ratchet-like wheel thereon. The device is manually placed upon the table of a vertically oriented band saw blade with the teeth of the wheel engaging the teeth of the blade, and the wheel is rotated to advance the blade by one tooth for each cog of the wheel. The cogs of the wheel also produce a scraping action which removes some metal from each tooth as the wheel is turned to advance the blade, thus sharpening the blade. No means of mechanically securing the Wright sharpener to the saw is disclosed, nor is any automation or provision for different tooth rake disclosed. The present invention provides an electrically powered sharpener which provides for each of the above functions.
U.S. Pat. No. 2,117,801 issued on May 17, 1938 to Rudolph Heino, titled "Lumber Saw Sharpener," describes a device for sharpening a radial or circular saw, rather than a band saw. Each of the sharpening stones is pivotally positioned between two plates. The pivotal action is required in order to allow each of the stones to follow the edge of the respective tooth as the blade is rotated. Accordingly, the Heino sharpener cannot be adjusted for different tooth rake or hook angles, as provided by the present invention. Also, no automatic shutoff or tooth pitch adjustment means is provided by Heino.
U.S. Pat. No. 3,802,299 issued on Apr. 9, 1974 to Vladimir V. Idel, titled "Band Saw Sharpening Machine," describes a machine having blade tooth rests at different angles, which impart different forces to the blade to cause it to advance periodically with the action of the grinding wheel. No power means for operating the advance mechanism is disclosed. The Idel patent disclosure refers to mechanisms for feeding the blade both longitudinally and transversely relative to the grinding wheel, thus requiring that the blade be removed from the saw before the Idel sharpener may be used on the blade, unlike the present sharpener which sharpens the blade in place on the saw. Also, the Idel sharpener removes more metal from the blade than does the present sharpener, as Idel uses a force normal to the sharpening wheel as a component of the blade advance mechanism, thereby causing the sharpening wheel to bear against the back of each tooth.
U.S. Pat. No. 3,822,613 issued on Jul. 9, 1974 to Vladimir V. Idel, titled "Bandsaw Grinder," describes a device again requiring the saw blade to be removed from the saw and placed into the grinder. Idel discloses a friction braking mechanism for stopping the blade for each cut, with the present invention providing a similar function but completely different structure for carrying out the braking operation. Idel does not disclose any advance means for the blade, nor any means of adjusting the depth or angle of the cut made by the grinding wheel, which features are provided by the present band saw blade sharpener.
U.S. Pat. No. 3,929,040 issued on Dec. 30, 1975 to Vladimir V. Idel, titled "Band-Saw Sharpening Machine," describes a saw blade positioning fixture for holding and supporting a continuous loop of band saw blade during the sharpening process. The blade must be removed from the saw for installation and sharpening in the Idel fixture, whereas the present sharpener is secured to the saw and sharpens the blade in its installed location in the saw. No specific sharpening, adjusting, blade positioning, or blade advance means is disclosed in the Idel '040 patent, each of which features are provided by the present band saw blade sharpener invention.
U.S. Pat. No. 4,064,770 issued on Dec. 27, 1977 to Vladimir V. Idel, titled "Machine For Sharpening Band Saw Teeth," describes a blade braking device similar to that disclosed in U.S. Pat. No. 3,822,613 to the same inventor and discussed further above. Again, the blade must be removed from the saw for sharpening using any of the Idel sharpening devices. The device of the Idel '770 patent provides a momentary brake release during the cutting or grinding operation on the blade, in order to release the tension on the blade being held in the sharpening fixture. Idel is also concerned about vibration of the blade during the sharpening operation, with no braking force provided on the blade, as he provides spring means to dampen such vibration. The present sharpener sharpens the blade in its installed position on the saw, with the saw providing constant tension on the blade and precluding any requirement for momentary brake devices and the like.
U.S. Pat. No. 5,088,358 issued on Feb. 18, 1992 to James Emter, titled "Automatic Dual-Side Saw Blade Grinder Having Common Blade Advancement And Clamp Actuator And Method Of Using Same," describes a pneumatic advance mechanism for advancing the teeth of a radial or circular saw. The saw blade must be removed from the saw mechanism for sharpening, unlike the present sharpener which is installed on the saw. The present mechanism utilizes a single electric motor to provide blade band advance and also to cycle the grinding or cutting wheel to sharpen each individual tooth of the saw blade, unlike the Emter mechanism.
French Patent Publication No. 2,343,550 published on Oct. 7, 1977 illustrates a device for sharpening a band saw blade, with the device having separate motors for blade advance and operating the sharpening wheel. No means is apparent for attaching the device to an existing band saw, as provided by the present device.
International Patent Publication No. 89/11,937 published on Dec. 14, 1989, titled "Apparatus And Process For The Grinding Of A Profile Of A Band Saw," describes a band saw blade sharpener using a sanding belt with a small radius pressure roller to work the belt into each tooth of the band. The sanding belt mechanism is unlike the grinding wheel sharpener of the present invention. Also, while the publication uses the term "band saw" throughout, the term refers only to the blade of the saw, not the entire saw mechanism. The blade must be removed from the saw for sharpening using the sharpener of this international publication, unlike the present invention which sharpens the blade in place on the saw.
European Patent Publication No. 473,364 published on Feb. 15, 1995, titled "An Apparatus For Sharpening Saw Blades," describes an apparatus for sharpening various types of saw blades, with a mechanical linkage serving to oscillate the grinding motor and wheel as a crank is manually turned to cycle the mechanism. As in each of the other devices discussed above, the blade must be removed from the saw in order to be sharpened using the device disclosed in the European publication. Moreover, the manual mechanism for advancing the blade and moving the cutting wheel are unlike the fully automated mechanism of the present invention.
Finally, the Brewco Company manufactures a combination band saw blade sharpener and tooth setter, using an electric motor for positioning the sharpening wheel and advancing the blade. However, the Brewco device cannot be attached to an existing band saw. Rather, the Brewco sharpener is a separate device, having its own stand, and requiring the band saw blade to be removed from the saw for sharpening using the Brewco device, as in the case of each of the other sharpening devices discussed further above and known to the present inventor. Also, the Brewco device does not provide any means of automatically stopping the blade advance when all of the teeth have been sharpened, which automatic stopping means is provided by the present band saw blade sharpener invention.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.